Please help algebra not hard
2 answers:
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Answer:
And if we solve for a we got
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the hourly rates of a population, and for this case we know the distribution for X is given by:
For this part we want to find a value a, such that we satisfy this condition:
(a)
(b)
Both conditions are equivalent on this case. We can use the z score again in order to find the value a.
As we can see on the figure attached the z value that satisfy the condition with 0.80 of the area on the left and 0.20 of the area on the right it's z=0.842. On this case P(Z<0.842)=0.8 and P(z>0.842)=0.20
If we use condition (b) from previous we have this:
But we know which value of z satisfy the previous equation so then we can do this:
And if we solve for a we got
Answer:
The difference in the areas of the cross section is 32 m²
Step-by-step explanation:
The given parameters are;
The height of the rectangular pyramid = 8 meters
The length of the base of the pyramid = 7 meters
The width of the base of the pyramid = 15 meters
Whereby triangular cross sections are formed through the vertex and perpendicular to the base, and to each other, we have;
The sides of the two triangles consists of the following;
1) Two slant height of the pyramid each
2) The two perpendicular lines joining the midpoints of the opposite sides of the base of the pyramid with length equal to the length of the adjacent side to the sides from which they are drawn which are 15 meters and 7 meters
3) The two lines and the corresponding slant height form triangles cross section which are perpendicular to each other.
the slant height, , is given as follows;
= √(8² + (15/2)²) ≈ 10.966
For the triangular cross section with base = 15 m
The area of the cross section = 1/2 × Base₁₅ × Height = 1/2 × 15 m × 8 m = 60 m²
For the triangular cross section with base = 7 m
The area of the cross section = 1/2 × Base₇ × Height = 1/2 × 7 m × 8 m = 28 m²
The difference in the areas of the cross section = 60 m² - 28 m² = 32 m².
